The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A057940 Number of prime factors of 4^n + 1 (counted with multiplicity). 9
 1, 1, 2, 1, 3, 2, 3, 1, 4, 2, 3, 3, 4, 2, 6, 2, 4, 4, 4, 2, 6, 3, 5, 3, 7, 3, 6, 3, 3, 4, 5, 2, 6, 4, 7, 5, 5, 4, 10, 3, 5, 5, 5, 4, 11, 2, 4, 3, 6, 6, 9, 2, 4, 6, 7, 5, 8, 3, 7, 6, 6, 4, 10, 2, 10, 7, 6, 4, 8, 4, 6, 7, 5, 2, 14, 4, 9, 5, 4, 4, 10, 4, 6, 8, 11, 4, 8, 3, 4, 8, 11, 4, 9, 5, 10, 4, 9, 8, 12, 6 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Max Alekseyev, Table of n, a(n) for n = 1..553 (first 531 terms from Amiram Eldar) S. S. Wagstaff, Jr., The Cunningham Project FORMULA a(n) = A057957(2n) - A057957(n). - T. D. Noe, Jun 19 2003 a(n) = Omega(4^n + 1) = A001222(A052539(n)). - Wesley Ivan Hurt, Jan 28 2014 a(n) = A054992(2*n). - Amiram Eldar, Feb 01 2020 MAPLE with(numtheory); A057940:=n->bigomega(4^n + 1); seq(A057940(n), n=1..100); # Wesley Ivan Hurt, Jan 28 2014 MATHEMATICA Table[PrimeOmega[4^n + 1], {n, 100}] (* Wesley Ivan Hurt, Jan 28 2014 *) CROSSREFS bigomega(b^n+1): A057934 (b=10), A057935 (b=9), A057936 (b=8), A057937 (b=7), A057938 (b=6), A057939 (b=5), this sequence (b=4), A057941 (b=3), A054992 (b=2). Cf. A001222, A052539, A057957, A274903. Sequence in context: A278573 A108663 A307314 * A097285 A057432 A302295 Adjacent sequences:  A057937 A057938 A057939 * A057941 A057942 A057943 KEYWORD nonn AUTHOR Patrick De Geest, Oct 15 2000 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified May 17 13:23 EDT 2022. Contains 353746 sequences. (Running on oeis4.)